Mr Joyce - the most senior government figure to weigh into the furore so far - said that social security recipients who owe the government "are not criminals" but need to settle the debts in the interest of taxpayers.

"I make no apology for making sure that those who didn't need it, who got it, pay the money back," the Nationals leader told ABC.

"We make no apology for the fact that we are trying to make sure we are more efficient, have a wider grasp of those who might have received payments in error."

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"I make no apology for making sure that those who didn't need it, who got it, pay the money back": Deputy Prime Minister Barnaby Joyce.Credit:Andrew Meares

Under the new system, 20,000 discrepancy notice letters are now being sent out each week - up from 20,000 per year. The letters are automatically generated from data-matching with Australian Taxation Office information. Since the lead-up to Christmas, the project has been criticised for miscalculating oversized bills and targeting people who have no debts payable.

"It is about time that Malcolm Turnbull got on top of this issue. It is about time that the government showed some compassion and some leadership," he said in a press conference, flanked by two of his constituents affected by the clawback.

One was Curtis Dickson, 31, who said he had been forced onto a repayment plan for a $750 debt he does not owe. The other was Tony Barbar, 29, who said Centrelink was incorrectly pursuing him for $4500 of debt based on payments received in 2010, when he was on sick leave and undergoing cancer treatment.

Like other critics of the system, Mr Albanese zeroed in on the number of people who have received discrepancy or debt notice letters but do not owe anything.

He also said the avenues for disputing Centrelink decisions were not adequate and that there were not enough employees in the Department of Human Services to handle the issue, thanks to the "slash and burn" approach of the government.

"I'm very sympathetic with the Centrelink staff who are in offices today with vulnerable people coming in and having to tell them to go away, and make a phone call, that they are unable to provide them with any assistance on the spot," Mr Albanese said.

On Friday, Guardian Australia reported the former - and short-lived - head of the government's digital transformation, Paul Shetler, describing the Centrelink debt recovery project as "cataclysmic" and dangerous, without enough human oversight "because their algorithms are flawed in the first place".

He has maintained that the process for resolving discrepancies and debts with Centrelink is straightforward and criticised Labor for undermining a project worth billions of dollars to the budget.

After receiving the initial letter saying that a discrepancy has been detected, people are given 21 days to confirm or update information, after which any resulting debts are pursued. Some people have been required to provide supporting documentation like pay slips and bank statements.

The main issues raised with the system are that it retrospectively miscalculates eligibility for payments by averaging out income across the year, in line with ATO protocol, whereas Centrelink relies on regular income reporting that shows the often fluctuating levels of fortnightly income.

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It has also counted some income twice because the names of employers have been different in the ATO and Centrelink systems. On top of this, some people have complained that - up to six years on from when they were receiving payments - they have not kept the necessary documentation to contest decisions.